The present invention relates to internal combustion engines; more particularly, to devices for securing fuel injectors into fuel distribution rails; and most particularly, to a clip for providing such securing and also preventing subsequent rotation of the fuel injector with respect to the fuel distribution rail and engine.
Means for attaching and securing of fuel injectors to fuel distribution rails of internal combustion engines is well known. Typically, a formed metal clip is employed to urge the body of a fuel injector into a cup-shaped socket element previously pressed into a port in the fuel rail, the injector body having means such as an O-ring for sealing against the inner surface of the socket. See, for example, U.S. Pat. Nos. 6,276,339 and 6,637,411.
In 4-valve engines, the relationship between the fuel injector spray pattern and the intake valves in the valve port can be critical and requires a specific orientation of the fuel injector tip to the intake valves. In such engines, the fuel injector body must be specifically oriented rotationally with respect to the rail and socket, and be prevented from rotation during its working lifetime. The fuel rail pre-assembly including fuel injectors must resist rotation of the injectors while the pre-assembly is being shipped, while it is being installed into an engine, during engine installation into a vehicle, and at any time an injector of the fuel rail is bumped during engine maintenance as well as while being subjected to xe2x80x9cin usexe2x80x9d forces.
U.S. Pat. No. 6,481,420 discloses a clip having anti-rotation capabilities. The clip has a flat, C-shaped base that is formed to slide into, and be retained in, an annular groove in the injector body. A plurality of upstanding tangs extend from the base to receive and substantially surround an annular flange on a fuel rail socket. An alignment protrusion is also provided on the clip to interface with a notch on the annular flange to prevent axial rotation of the fuel injector relative to the fuel rail socket (assuming that the socket has been correctly oriented during its installation into the fuel rail).
The alignment protrusion of this device can provide resistance to relatively low rotational forces on the fuel injector; however, progressively higher torque can deform the clip base and twist the protrusion out of engagement with the socket flange. At least one automotive manufacturer has now increased the minimum torque resistance of such a joint from 1.5 Nm to 3.0 Nm, and, because of the bending moment placed on the base of the alignment protrusion when the injector is axially twisted, the above structure will fail at such elevated torque levels.
U.S. Pat. No. 5,803,052 also discloses a clip having anti-rotation capabilities. The clip has a flat, C-shaped base that is formed to slide into, and be retained in, an annular groove in the injector body. Opposed sidewalls extend from the base and include horizontal slots for capturing a radial flange on a fuel rail socket to position and retain the injector body axially within the cup. A third sidewall connecting the opposed sidewall also extends from the base and includes a window for receiving radial tangs on both the fuel injector body and the cup flange, thereby locking the rotational relationship between the body and flange.
This configuration may be capable of resisting a rotational torque greater than the clip disclosed in U.S. Pat. No. 5,803,052. However, a drawback of this configuration is that the clip cannot be installed until after the injector has been inserted into the socket, whereas in some manufacturing processes it would be desirable to install an anti-rotation clip onto either the fuel injector or the socket prior to their being joined.
It is a principal object of the present invention to provide means for joining a fuel injector into a fuel rail to prevent rotation of the fuel injector at elevated torque levels.
It is a further object of the invention to provide such means including a joining clip wherein the clip may be installed onto the fuel injector body prior to insertion of the fuel injector into the fuel rail socket.
Briefly described, an anti-rotation clip for joining a fuel injector body to a fuel rail socket includes a flat, C-shaped base that is formed to slide into, and be retained in, an annular groove in the injector body. A pair of curved tangs extend from the base to straddle a longitudinal rib on the injector body to prevent rotation between the clip and the injector. Opposed sidewalls extend from the base in the opposite direction. A window is formed in each sidewall for receiving a radial flange of a fuel rail socket to correctly position the fuel injector axially within the socket. Each window is divided by a locking bar that is received in a notch in the socket flange to prevent rotation between the clip and the socket. The radial positions of the injector rib and flange notch are selected such that the injector, when assembled to the fuel rail socket, is properly oriented with respect to the engine requirements. The combination of the tangs and rib, and of the windows, bar, and notch, is sufficiently robust to withstand an imposed torque of at least 3 Nm between the fuel injector and the fuel rail socket.